This book has been designed to cover the content of the 'Radiocommunications' module officially scheduled for the first year of the Master's degree in telecommunications systems. It is also intended, in general, for all students pursuing studies in the field of telecommunications within universities and engineering schools in Algeria.This work contains five chapters allowing the reader, whether a student or a teacher, to understand various theoretical concepts related to radiocommunications. The objectives focus on deepening the understanding of electromagnetic field concepts, studying the behavior of radio waves at ground level and in the atmosphere (troposphere, stratosphere, and ionosphere), mastering the design and sizing of a radiocommunication system, as well as studying space communications and satellite links. At the end of each chapter, exercises are provided with their solutions to help the student test their acquired knowledge and prepare for tests and exams that may be encountered in their journey through the field of radiocommunications.